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From 8c30fba366c6814c7bb1795fdda16265eb48efb0 Mon Sep 17 00:00:00 2001
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From: Alan Modra <amodra@gmail.com>
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Date: Sun, 8 Nov 2015 09:29:00 -0800
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Subject: [PATCH 06/11] ELF unexec: _OBJC_ symbols in bss sections
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This code assumed that there was only one bss section. Rather than
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checking for a particular index, check the section type. Also, handle
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the possibility that the section was SHT_NOBITS originally and is
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unchanged, in which case no clearing is needed (and sh_offset isn't
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necessarily valid, which can lead to a wild memset).
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* unexelf.c (unexec): Properly handle _OBJC_ symbols in bss sections.
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---
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src/unexelf.c | 31 ++++++++++++++++++-------------
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1 file changed, 18 insertions(+), 13 deletions(-)
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diff --git a/src/unexelf.c b/src/unexelf.c
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index 286ba2e..df99f92 100644
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--- a/src/unexelf.c
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+++ b/src/unexelf.c
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@@ -1176,20 +1176,25 @@ temacs:
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"_OBJC_", sizeof ("_OBJC_") - 1) == 0)
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{
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ElfW (Shdr) *new_shdr = &NEW_SECTION_H (symp->st_shndx);
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- ptrdiff_t reladdr = symp->st_value - new_shdr->sh_addr;
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- ptrdiff_t newoff = reladdr + new_shdr->sh_offset;
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-
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- /* "Unpatch" index. */
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- nn = symp->st_shndx;
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- if (nn > old_bss_index)
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- nn--;
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- if (nn == old_bss_index)
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- memset (new_base + newoff, 0, symp->st_size);
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- else
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+ if (new_shdr->sh_type != SHT_NOBITS)
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{
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- ElfW (Shdr) *old_shdr = &OLD_SECTION_H (nn);
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- ptrdiff_t oldoff = reladdr + old_shdr->sh_offset;
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- memcpy (new_base + newoff, old_base + oldoff, symp->st_size);
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+ ElfW (Shdr) *old_shdr;
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+ ptrdiff_t reladdr = symp->st_value - new_shdr->sh_addr;
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+ ptrdiff_t newoff = reladdr + new_shdr->sh_offset;
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+
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+ /* "Unpatch" index. */
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+ nn = symp->st_shndx;
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+ if (nn > old_bss_index)
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+ nn--;
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+ old_shdr = &OLD_SECTION_H (nn);
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+ if (old_shdr->sh_type == SHT_NOBITS)
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+ memset (new_base + newoff, 0, symp->st_size);
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+ else
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+ {
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+ ptrdiff_t oldoff = reladdr + old_shdr->sh_offset;
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+ memcpy (new_base + newoff, old_base + oldoff,
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+ symp->st_size);
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+ }
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}
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}
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#endif
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--
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2.7.4
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